Giardiasis in lambs at pasture.

Faecal samples from a group of lambs at pasture were screened at weekly intervals for nine weeks for the presence of Giardia species using a modified zinc sulphate flotation method. Fifty-nine of 86 lambs (68.6 per cent) excreted giardia cysts on one or more occasions. They were first detected at approximately three weeks of age and the highest incidence of excretion of cysts occurred when the lambs reached a mean age of 37 days. The lambs had diarrhoea but it was attributed to the presence of Eimeria ovinoidalis.